1. Avalanche Hazards in Mountainous Terrain

2. Avalanche Hazards Terminal Learning Objective Action: Move safely in avalanche terrain. Condition: Under field conditions in avalanche terrain, given beacons, probes, shovels, inclinometer, military snowshoe, bindings, ski poles, survival rucksack (packed IAW training schedule), vapor barrier boots, rucksack (with a minimum load of sleeping bag, sleeping pad, extra pair of socks, extra pair of mitten inserts, additional packing list items may be prescribed by unit), ECWCS, other issued cold weather clothing items, ballistic helmet, LCE with 2 quarts of water, and weapon Standard: Student evaluated avalanche potential in different areas. Student chose safe routes in terrain with avalanche potential. Student utilized special equipment to recover personnel and equipment from a mock avalanche scenario.

4. Definition: An avalanche is a mass of snow sliding down a mountainside. Avalanches are also called snow slides; there is no difference in these terms. What is an avalanche?

5. Types of Avalanches 1. Loose snow avalanche or point release avalanche 2. Slab avalanche

6. ALTHOUGH USUALLY SMALL,THEY CAN TRIGGER A SLAB TO RELEASE Point Release Avalanche

7. CROWN TRACK RUNOUT Slab Avalanche

10. Avalanche Debris

12. Recognizing the Hazard

13. Can it slide? Is it capable of producing avalanches? How do I measure the Slope Angle? Terrain characteristics Terrain

14. 30-45º DANGER ZONE 20-60 DEGREES NATURALLY SLUFF OFF MINIMUM DANGER 20º 60º Slope Angle: Can it Slide?

15. Site Along > Site Along > This Edge This Edge > How do I measure the slope angle?

16. < 0 Degrees 0 Degrees > 90 Degrees 90 Degrees

17. Surface of > Slope > EyePoint > Sight the Angle from inside the Snowpack by Digging Deep Enough for the Protractor

18. Slope Shape CONCAVE SAFER MORE STRESS CONVEX

19. Grassy slopes or smooth rock make for an unstable slope Jumbled rock, deadfall will anchor bottom layers Trees will anchor surrounding snow, but beware of snow above tree line coming down Anchors

20. CREEK BED CLIFF Terrain Traps Gullies,couloirs,creek beds,canyons

21. Terrain Traps

22. Snowpack: Ingredients for an Avalanche

23. Weather Wind Action Precipitation Slope Aspect Temperature

24. Wind Loading Wind moves snow from one area to another forming a wind slab WINDWARD LEEWARD

25. WIND LOADING WIND SCOURING Wind Loading

26. Side Loading

27. Cornice

30. Snow Fall Slush (Rain Caused) Precipitation

31. North facing slopes are avalanche prone in mid-winter South facing slopes are more dangerous in spring and on sunny days Slope Aspect

32. Wet slab avalanches from excess warmth or rain Determines bonding of the snow through the freeze thaw cycle Temperature

33. Ignorance of the hazard Mission focused Traveled through an area many times and it was always safe before Brain not engaged Don’t know don’t go; you control this People: Human Factors

34. Additional Snow Fall (more than 1 inch an hour) Windloading Cornice Breaks Personnel/Vehicles Overloading

35. Trigger avalanche(s) prior to moving Must be detonated in the correct position Could give away position Demolitions

36. General Indicators of Avalanche Prone Terrain Evidence of previous slides Steep slopes between 30-45 degrees Recent heavy snowfall adding to the weight of snowpack Visible fracture lines in the snow Audible settling of the snowpack Severe temperature changes Lee slopes Snow plumes and high winds Slushy spring snow Outside force to break the stability

37. Tree Flagging

38. Route Selection: Is there a SAFER route?

39. Route Selection: Travel in Valleys Traffic in the valley floor can trigger slides from above. How will you know the risks? Consider your Run-out Angle for safe travel in valleys

40. The MEASURED angle from you to the potential avalanche start point. 19 Degrees is considered safe Run-Out Angle

41. Ski-pole Snow-pit Shovel Shear Rutschblock Test Banzai Test Hazard Evaluation: Snow Pack Analysis

43. Necessary Equipment in Avalanche Country Avalanche Probe Shovel Transceiver Slope angle measuring device

44. Crossing a Questionable Slope Loosen equipment Remove pole straps from wrists Disconnect safety leashes from skis Loosen rucksack straps Cross one at a time with a watch posted

45. If Caught in an Avalanche Attempt to release skis Remove heavy rucksack Use Swimming Motion Create an Air Space Try to find the surface

46. If you witness others caught in an avalanche Keep your eyes on the victims. Note terrain traps Look for surface clues Organize search Don’t go for help. YOU ARE THE HELP!

47. Avalanche Hazards Summary Action: Move safely in avalanche terrain. Condition: Under field conditions in avalanche terrain, given beacons, probes, shovels, inclinometer, military snowshoe, bindings, ski poles, survival rucksack (packed IAW training schedule), vapor barrier boots, rucksack (with a minimum load of sleeping bag, sleeping pad, extra pair of socks, extra pair of mitten inserts, additional packing list items may be prescribed by unit), ECWCS, other issued cold weather clothing items, ballistic helmet, LCE with 2 quarts of water, and weapon Standard: Student evaluated avalanche potential in different areas. Student chose safe routes in terrain with avalanche potential. Student utilized special equipment to recover personnel and equipment from a mock avalanche scenario.